Automatic alarm setting system

ABSTRACT

An automatically resetting alarm system operatively joined to contacts of a timer. The timer contacts having been set to sound an alarm at a desired point of time, are automatically reset after the alarm for sounding the next alarm.

United States Patent 1191 Herrnreiter 45] Apr. 17, 1973 AUTOMATIC ALARM SETTING SYSTEM Inventor: Siegfried Herrnreiter, 2840 West Montrose, Chicago, 111. 60618 Filed: May 10, 1971 Appl. No.: 141,803

U.S. Cl ..340/309.1, 200/38 D Int. Cl. ..HOlh 43/10 Field of Search 340/309. l-309.6; 335/166, 128, 200, 133;

200/38 D, 38 C, 38 R; 317/155; 74/3.5, 3.52,

References Cited UNITED STATES PATENTS 10/1964 Pardee ..340/3091 1,645,019 10 1927 Opperman ..335/166 1,503,981 8/1924 Carichoff ..335/200 x 3,372,250 3/1968 Douglas ..200/38 1) 2,976,471 3 1961 Harris ..200/38 c 2,942,161 6/1960 Bell ..317/155 3,270,493 9/1966 Wallace ....340 309.1 3,109,077 10/1963 Horman ..335/133 1,396,370 11/1921 111615116 ..340/3094 Primary Examiner-John W. Caldwell Assistant ExaminerWilliam M. Wannisky AI10rneySilverman & Cass 5 7 ABSTRACT An automatically resetting alarm system operatively joined to contacts of a timer. The timer contacts having been set to sound an alarm at a desired point of time, are automatically reset after the alarm for sounding the next alarm.

8 Claims, 8 Drawing Figures PATENTEuAPRmma 34,728,707

FIG'IA I w v Inve nror 6 IEGFRIED HERRNREITER 'BYZ & QM

ATTYS.

AUTOMATIC ALARM SETTING SYSTEM BACKGROUND OF THE INVENTION The invention relates to automatic alarm systems for clocks or timers and in particular to devices for automatic resetting of the alarm.

DESCRIPTION OF THE PRIOR ART Alarm systems have been known wherein the alarm is sounded when the set alarm time is reached. The alarm is stopped by a person pushing a button thereby blocking the alarm of the clock.

If is intended to reset the alarm so that it will sound again 12 or 24 hours later, the button has to be removed from the blocking position, thereby releasing the alarm system.

A person using an alarm clock may be interested that the next alarm is sounded again after 24 hours and not after 12 hours. The typical case is that of a person wishing to be awakened at a certain hour in the morning in order to get up and prepare for going to work. Such person is not interested to have the alarm sounded at the same point of time in the evening hours. As an example, a person wishing to be awakened at 6:00 A.M. every morning does not want to hear the alarm at 6:00 P.M.. In order not to be bothered by an alarm at 6:00 P.M. he has to block the alarm in the morning and release the alarm button sometime after 6:00 P.M.. If

he releases it before that time the alarm will sound at 6:00 P.M., which many people may consider a nuisance. I g

The automatic release systems of the present invention provides for a device to be associated with a clock or timer wherein, upon the sounding of the alarm a button is pushed by a person whereby the alarm is stopped and automatically reset to a point in time 24 hours subsequent to the first alarm.

The invention also provides for an alarm system in which a dial is used having markings in hours ranging from 1 to 24. Alternatively, a dial may be provided having markings ranging from 1 A.M. to 12 A.M. and l P.M. to 12 P.M..

SUMMARY OF THE INVENTION Apparatus for automatically resetting an alarm device in cooperation with a timer system comprising in an electric circuit timer contacts capable of being set to close at a desired point of time, a relay and a switch operated by a pushbutton and a spring such as to automatically reset the next alarm.

BRIEF DESCRIPTION OF THE DRAWINGS Flg. l is a perspective view of the alarm system according to the invention.

FIG. 1A is a partial sectional view of FIG. 1 as seen from a radial plane taken on a line IA-lA and in the direction indicated.

FIG. 2 is a side elevational, partly schematic view of another embodiment of the alarm system having a contact assembly differing from that of FIG. 1.

Flg. 3 illustrates an electric circuit arrangement of the alarm system according to the invention, using a pivoting switch.

FIG. 4 shows another electric circuit using relay and switch systems different from those of FIG. 3.

FIG. 5 illustrates a locking arrangement for the pushbutton.

FIG. 6 shows a device for two' lamps indicating twelve hour periods of A.M. and P.M..

FIG. 7 is an enlarged partial view of the indicating device of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, a small gear wheel 21 is shown as being rotatable on an axle 22 and in driving connection with a large gear wheel 23. The diameters of'the wheels 21 and 23 are selected to be such as to obtain a speed ratio of l to 24. The small wheel 21 may be an hour wheel of a regular clock mechanism, i.e., a wheel which will make one revolution in one hour. The clock mechanism is of no concern to the present invention and is therefore not described here. The large wheel 23 will make a hill revolution in 24 hours. The clock mechanism and the alarm resetting system are arranged in a common housing 20 (not completely shown).

A dial 25 is mounted at the front end of the housing, as indicated on the right side of FIG. 1 of the drawing. The dial may have markings ranging from 1 to 24 or 1 to 12 A.M. or 1 to 12 P.M. as noted earlier. The large wheel 23 is provided with a central opening 27 in which the spindle 24 can freely .rotate. A stationary annularplate 26 is mounted in'a conventional way and secured to the housing, and a contact ring 28 is secured in a conventional manner to the annular plate 26, as indicated in FIG. 1A.

A flexible time contact arm 30 has one end thereof fastened to the spindle 24 so asto be rotatable therewith. The other end of the arm 30 is provided with a contact member 31. A hand 32 is secured to the front end of the spindle 24. A knob 34 is fastened to the rear end of the spindle 24. The knob 34 may be knurled or may be made up of a plurality of ring members so as to facilitate holding the knob tightly for setting the alarm time.

The hand 32 is rotatable in front of the dial 25. The setting of the alarm is done by turning the knob 34, thereby moving hand 32 over the markings of dial 25 until the hand reaches the hour at which the alarm is intended to be sounded.

A cog 36 is attached to the wheel 23 so as to be capable of pressing the contact member 31 to contact ring 28 when the wheel 23 which is driven by wheel 21 reaches a position wherein the cog 36 is aligned with contact 31.

Electric wires 33, 35 connected to contact ring 28 and contact arm 30 respectively lead to terminals 37,

39 which are part of the alarm circuit. When contact member 31 is pressed against contact ring 28, the contact is made which is required to close the alarm circuit.

In FIG. 2 an embodiment of the invention is illustrated wherein the contact ring 28 is replaced by an arm 38 which is rigidly mounted on the spindle 24. The arm 38 and the time contact arm 30 are always facing one another. The arm 38 and the contact arm 30 are rotated together by the turning of the knob 34, but contact between them is made only when the cog 36 on wheel 33 reaches a position, wherein the cog 36 touches the arm 30 and presses the contact member 31 against the arm 38, thereby making the contact required for closing the alarm circuit.

FIG. 3 illustrates an electric alarm circuit according to the inventive concept. The contact arrangements by ring 28 and arm 30 in FIG. 1 and by arms 38 and 30 in FIG. 2 are presented here in FIG. 3 by contacts 44 and 46. Terminals 48 and 50 are to be connected to an electric power source. A relay 52 arranged in a first circuit branch has a first lead 54 connected to the contact 46. The second lead of relay 52 is connected over lines 56 and 58 to terminal 48 of the electric source.

A second circuit branch arranged in parallel to the first circuit branch is also connected to the electric source and contacts 44, 46, and comprises a switch 60 of special construction which will be explained hereinafter, and a bell 62. Switch 60 and bell 62 are arranged in series relative to one another. The switch is connected to contact 46 via lead 64, and to the bell by lead 66. The bell is connected to the electric source terminal 48 via lead 68 and the earlier noted line 58.

The switch 60 has two arms 70 and 72 which are rigidly joined to one another and are pivotable around a center point 74. A spring 76 is fastened at one end to the housing, the other end being connected to arm 72. The spring 76 urges arm 72 to keep contact 80 closed. A push-button 82 is arranged such that when it is pushed down against spring 86 it moves arm 70 pivotingly out of its normal position, opening contact 84, and also moves arm 72 against the power of spring 76, opening contact 80.

In operation, when contacts 44 and 46 are closed by the cog 36 upon reaching the alarm time, as set forth above, relay 52 is energized but does not attract contact 78 since the relay winding is dimensioned such as to produce an electro-magnetic force less than one capable of overcoming the force of spring 76. Therefore, contact 80 remains closed. The bell 62 is sounded since it is now connected to the electric source via terminal 50, closed contacts 44, 46, lead 64, closed contact 84, arm 70, arm 72, closed contact 80, leads 66, 68, 58 and terminal 48.

The push-button 82 is now momentarily pressed down, whereby arms 70 and 72 are pivoted out of position, opening contacts 84 and 80, and the alarm stops. Since the pivoting movement of arm 72 has moved contact 78 closer to relay 52, the relay is strong enough to now hold contact 78 in the attracted position, so that bell 62 continues to be silent despite the fact that the push-button has returned to its normal position under the impact of a spring 86 embracing the stem portion 87 below the head part 89 of the push button 82.

Upon the lapsing of a few seconds the cog 36 moves on, by virtue of the movement of wheel 23, contacts 44 and 46 are opened and relay 52 is deenergized and releases contact 78. Arm 72 is restored to its normal position by spring 76, the contact 80 is closed and the alarm is thereby reset. The alarm will resound again when the same point of time is reached, i.e., 24 hours later.

FIG. 4 illustrates another embodiment of the inventive concept, differing particularly with regard to the electric circuit of FIG. 3.

In this embodiment relay 92 has two windings 94 and 96. The winding 94 is, in analogy to the winding of relay 52, dimensioned such that its power of attraction is not sufficient to initially pull the relay contact arm 98 out of its normal position. However, the two relay windings 94 and 96 together do produce a force sufficient to move contact arm 98 from contact 100.

A contact assembly 104 comprises two flexible contact arms 106 and 108 which are separated by insulation elements 110, 111.

In the normal position, contact arm 106 is in contact with terminal 114. Push-button 82 is of the same structure as the push-button in FIG. 3. When the push-button is pressed down momentarily the contact with terminal 114 is broken and the arm 108 makes a bridging connection between contacts 1 16 and 118.

In operation, when contacts 44 and 46 are closed by the cog 36 as described earlier with respect to FIGS. 1 and 2, relay winding 94 is energized over terminal 48, leads 120, 121, 123, 130, 125, contact arms 46, 44 and terminal 50, but the winding 94 does not attract contact arm 98 due to insufficient force of winding 94. On the other hand, bell 62 is sounded since its circuit is closed via terminal 48, leads 120, 122, 124, 126, contact terminal 100, contact arm 98, lead 128, contact arm 106, contact terminal 114, leads 132, 130, 125, contact arm 46, contact terminal 44 and terminal 50.

Now push-button 82 is pressed down momentarily, opening contact at 114 and closing contact between arm 108 and terminals 116, 118. The second winding 96 of relay 92 is now energized over terminal 48, leads 120, 122, 134, 136, terminal 118, arm 108, terminal 116, leads 138, 125, arm 46, terminals 44 and 50. As noted earlier, the two windings 94, 96 of relay 92 pull the arm 98, thereby opening contact at 100. The opening of contact cuts off the bell 62 from the electric power source, and the bell is silent. Relay winding 96 is held through contact 102.

Upon the lapse of a few seconds, cog 36 passes on and away from contacts 44, 46, thereby opening the circuits for the two relay windings 94, 96. The relay 92 is deenergized and releases arm 98 which closes contact 100, thereby resetting the alarm.

In FIG. 5 an arrangement is illustrated whereby the push-button may be locked after it has been pushed down. This is to be done when it is desired to cut off the alarm for a longer period of time, i.e., when the user wishes not to be bothered by the alarm once every 24 hours. As an example, the user takes a vacation and does not want to be awakened at an early morning hour. In such event the push-button is pressed down as usual for cutting off the alarm, now however, it is not released but turned around by a few degrees. A lug 142 fastened to the bottom part of the push-button 82 is arranged such that when the push-button is pushed down the lug 142 passes an opening 144 in a plate 146, which is secured to the housing and located underneath spring 86. Once the lug 142 is below the plate 146 the head of the push-button 82 is turned around by a few degrees. The push-button is now locked in this position since the lug 142 is prevented from moving upward by the plate 146. Only when the push-button is turned back by the user so that lug 142 is beneath the opening 144, the push-button will, driven by the spring 86, move upward to its normal position.

In FIG. 6 a device is illustrated for indicating the twelve hour periods known as A.M. or P.M. The indicator includes two small lamps 172, 174 such as for example a green lamp for A.M. time and a red lamp for P.M. time. Two semiannular metal strips 152, 154 are fastened to two insulating members 156, 158 in a conventional manner. A wiping am 155 is mounted to the gear wheel 23 so as to rotate therewith. The strips 152, 154 are connected by beads 160, 162 respectively to a green or a red lamp. The lamps are connected on the other sides by leads 164, 166 to a common ground terminal 167. The wiping arm 155 is connected by a lead 169 to a battery terminal 170.

When the wiping arm is over any point of strip 152 the green lamp is connected to the battery and will be on indicating that the hand 32 is within the range of the twelve hours of the A.M. period. Analogously, the red lamp is turned on by the wiper arm 155 being over a point on strip 154 and indicates the P.M. period.

The insulating members are of small width. This is to assure that the time period in which the arm 155 slides over the insulating member is small. During this short period, as is obvious, no lamp is on. At all other times, the user will always be able to determine even if he is on a U-Boat whether the clock is on the A.M. or P.M. period, in other words, whether it is day or night.

It is believed that the foregoing adequately will enable those skilled in the art to appreciate and practice this invention and, if necessary, make modifications which would fall within the scope of the invention as defined by the accompanying claims.

What is sought to be protected by United States Letters Patent is:

lclaim:

1. Apparatus for automatic resetting of an alarm device associated with a timer system in a common housing, said apparatus comprising in an electric circuit which is connectable to an electric power source:

a. timer contact means for closing the electric circuit when the time set for the alarm is reached;

b. alarm means coupled in series to the timer contact means;

c. relay means connected in series with the timer contact means, and in parallel with the alarm means;

d. switch means arranged in series with the alarm means;

e. push-button means operatively connected to the switch means for disconnecting the alarm means, and

f. spring means for biasing a contact of the relay means, wherein the switch means comprise: an upper flexible arm and a lower flexible arm, a first insulating member secured to an end of each arm so as to keep them spaced apart, a second insulating member secured to and adjacent the other ends of the arms, the upper arm being associated with a normally closed contact, the lower arm being associated with two normally open contacts which are capable of being closed by the lower arm, wherein the normally closed contact is in series connection with the alarm means, and the two normally open contacts are in series connection with the relay means.

2. Apparatus as set forth in claim 1, and further comprising:

a. a spindle rotatably mounted in the housing, so as to traverse the timer contact means,

b. a knob rigidly fastened to one end of the spindle,

c. a hand rigidly secured to the other end of the spindle so as to be rotatable therewith,

a dial having hour markings thereon and mounted to the spindle at the other end thereof such that the spindle and the hand may be rotated by turning the knob, and the hand may be set at any desired point of time for sounding the alarm,

e. a gear wheel in meshing engagement with an hour wheel of the timer,

f. a cog member fastened to the gear wheel adjacent the periphery thereof and constructed and adapted such as to, upon reaching the timer contact means, press the contact elements towards one another, whereby the alarm circuit is closed, wherein the timer contact means comprise:

. a contact ring of electrically conducting material fastened to an annular plate, said plate being secured to the housing and having a central opening for receiving the spindle,

h. a flexible contact arm, one end thereof being rigidly secured to the spindle so as to be angularly aligned with said hand, and

i. a contact member attached at the other end of the flexible contact arm.

3. Apparatus as set forth in claim 1, and further comprising:

a. a spindle rotatably mounted in the housing, so as to traverse the timer contact means,

b. a knob rigidly fastened to one end of the spindle,

c. a hand rigidly secured to the other end of the spindle so as to be rotatable therewith,

. a dial having hour markings thereon and mounted to the spindle at the other end thereof such that the spindle and the hand may be rotated by turning the knob, and the hand may be set at any desired point of time for sounding the alarm,

e. a gear wheel in meshing engagement with an hour wheel of the timer,

f. a cog member fastened to the gear wheel adjacent the periphery thereof and constructed and adapted such as to, upon reaching the timer contact means, press the contact elements towards one another, whereby the alarm circuit is closed, wherein the timer contact means comprise:

a first contact arm, one end thereof being rigidly secured to the spindle, and

h. a second contact arm, one end thereof being rigidly secured to the spindle, the second contact arm being flexible and provided at the other end thereof with a contact member.

4. Apparatus as set forth in "claim 1, and further comprising:

a. a spindle rotatably mounted in the housing, so as to traverse the timer contact means,

b. a knob rigidly fastened to one end of the spindle,

c. a hand rigidly secured to the other end of the spindle so as to be rotatable therewith,

d. a dial having hour markings thereon and mounted to the spindle at the other end thereof such that the spindle and the hand may be rotated by turning the knob, and the hand may be set at any desired point of time for sounding the alarm,

ea gear wheel in meshing engagement with an hour wheel of the timer,

f. a cog member fastened to the gear wheel adjacent the periphery thereof and constructed and adapted such as to, upon reaching the timer contact means, press the contact elements towards one another, whereby the alarm circuit is closed, and further comprising indicating means including a first and a second insulating member secured to the housing, a first semi-annular metal strip the ends thereof being fastened to first sides of the insulating members, a second semi-annular metal strip the ends thereof being fastened to second sides of the insulating members, the metal strips being arranged in a plane parallel to and adjacent the gear wheel, a wiping arm insulatedly mounted to the gear wheel and adapted to be capable of rotatingly sliding over the metal strips, and signal means connected in an electric circuit to the metal strips.

5. Apparatus as set forth in claim 4, wherein the signal means comprise a first lamp and a second lamp, the lamps being of different colors, each lamp having a first terminal connected respectively to one of the metal strips, the second terminal of the lamps being connected to ground, the wiping arm being connected to an electric source.

6. Apparatus as set forth in claim 1, wherein the push-button means comprise a push-button including a head part and a stem portion, a second spring embracing the stem portion, the push-button being disposed facing the upper arm adjacent the second insulating member.

7. Apparatus as set forth in claim 6, wherein the push-button means further comprise plate means secured to the housing in a plane normal to the axis of the stem portion, a recess in the plate means, a lug member fastened to the lower end of the stem portion so as to extend therefrom in a plane parallel to the plate means, the lug member being constructed and adapted to traverse the recess of the plate means when the pushbutton is being depressed, whereby, upon the lug member reaching a position below the plate means, the push-button may be rotated and locked in position.

8. Apparatus as set forth in claim 6, wherein the relay means comprise:

a. a relay core,

b. a first winding around the core,

0. a second winding around the core disposed adjacent the first winding, the first winding being arranged in series with the timer contacts, the second winding being arranged in series with the two normally open contacts of the switch means and with the timer contacts,

(1. relay contact means including,

i. a contact arm, and ii. a normally closed contact, the contact arm and the normally closed contact being in series con- I nection with the timer contacts, the upper arm of the switch means and the alarm means, wherein the first relay winding is dimensioned such as to produce an electro-magnetic force of attraction sufficient to hold the relay contact arm in an attracted position once the contact arm has been moved there by the combined electro-magnetic force of attraction of the two relay windings. 

1. Apparatus for automatic resetting of an alarm device associated with a timer system in a common housing, said apparatus comprising in an electric circuit which is connectable to an electric power source: a. timer contact means for closing the electric circuit when the time set for the alarm is reached; b. alarm means coupled in series to the timer contact means; c. relay means connected in series with the timer contact means, and in paralleL with the alarm means; d. switch means arranged in series with the alarm means; e. push-button means operatively connected to the switch means for disconnecting the alarm means, and f. spring means for biasing a contact of the relay means, wherein the switch means comprise: an upper flexible arm and a lower flexible arm, a first insulating member secured to an end of each arm so as to keep them spaced apart, a second insulating member secured to and adjacent the other ends of the arms, the upper arm being associated with a normally closed contact, the lower arm being associated with two normally open contacts which are capable of being closed by the lower arm, wherein the normally closed contact is in series connection with the alarm means, and the two normally open contacts are in series connection with the relay means.
 2. Apparatus as set forth in claim 1, and further comprising: a. a spindle rotatably mounted in the housing, so as to traverse the timer contact means, b. a knob rigidly fastened to one end of the spindle, c. a hand rigidly secured to the other end of the spindle so as to be rotatable therewith, d. a dial having hour markings thereon and mounted to the spindle at the other end thereof such that the spindle and the hand may be rotated by turning the knob, and the hand may be set at any desired point of time for sounding the alarm, e. a gear wheel in meshing engagement with an hour wheel of the timer, f. a cog member fastened to the gear wheel adjacent the periphery thereof and constructed and adapted such as to, upon reaching the timer contact means, press the contact elements towards one another, whereby the alarm circuit is closed, wherein the timer contact means comprise: g. a contact ring of electrically conducting material fastened to an annular plate, said plate being secured to the housing and having a central opening for receiving the spindle, h. a flexible contact arm, one end thereof being rigidly secured to the spindle so as to be angularly aligned with said hand, and i. a contact member attached at the other end of the flexible contact arm.
 3. Apparatus as set forth in claim 1, and further comprising: a. a spindle rotatably mounted in the housing, so as to traverse the timer contact means, b. a knob rigidly fastened to one end of the spindle, c. a hand rigidly secured to the other end of the spindle so as to be rotatable therewith, d. a dial having hour markings thereon and mounted to the spindle at the other end thereof such that the spindle and the hand may be rotated by turning the knob, and the hand may be set at any desired point of time for sounding the alarm, e. a gear wheel in meshing engagement with an hour wheel of the timer, f. a cog member fastened to the gear wheel adjacent the periphery thereof and constructed and adapted such as to, upon reaching the timer contact means, press the contact elements towards one another, whereby the alarm circuit is closed, wherein the timer contact means comprise: g. a first contact arm, one end thereof being rigidly secured to the spindle, and h. a second contact arm, one end thereof being rigidly secured to the spindle, the second contact arm being flexible and provided at the other end thereof with a contact member.
 4. Apparatus as set forth in claim 1, and further comprising: a. a spindle rotatably mounted in the housing, so as to traverse the timer contact means, b. a knob rigidly fastened to one end of the spindle, c. a hand rigidly secured to the other end of the spindle so as to be rotatable therewith, d. a dial having hour markings thereon and mounted to the spindle at the other end thereof such that the spindle and the hand may be rotated by turning the knob, and the hand may be set at any desired point of time for sounding the alarm, e. a gear wheel in meshing engagement with an hour wheel of the timer, f. a cog member fastened to the gear wheel adjacenT the periphery thereof and constructed and adapted such as to, upon reaching the timer contact means, press the contact elements towards one another, whereby the alarm circuit is closed, and further comprising indicating means including a first and a second insulating member secured to the housing, a first semi-annular metal strip the ends thereof being fastened to first sides of the insulating members, a second semi-annular metal strip the ends thereof being fastened to second sides of the insulating members, the metal strips being arranged in a plane parallel to and adjacent the gear wheel, a wiping arm insulatedly mounted to the gear wheel and adapted to be capable of rotatingly sliding over the metal strips, and signal means connected in an electric circuit to the metal strips.
 5. Apparatus as set forth in claim 4, wherein the signal means comprise a first lamp and a second lamp, the lamps being of different colors, each lamp having a first terminal connected respectively to one of the metal strips, the second terminal of the lamps being connected to ground, the wiping arm being connected to an electric source.
 6. Apparatus as set forth in claim 1, wherein the push-button means comprise a push-button including a head part and a stem portion, a second spring embracing the stem portion, the push-button being disposed facing the upper arm adjacent the second insulating member.
 7. Apparatus as set forth in claim 6, wherein the push-button means further comprise plate means secured to the housing in a plane normal to the axis of the stem portion, a recess in the plate means, a lug member fastened to the lower end of the stem portion so as to extend therefrom in a plane parallel to the plate means, the lug member being constructed and adapted to traverse the recess of the plate means when the push-button is being depressed, whereby, upon the lug member reaching a position below the plate means, the push-button may be rotated and locked in position.
 8. Apparatus as set forth in claim 6, wherein the relay means comprise: a. a relay core, b. a first winding around the core, c. a second winding around the core disposed adjacent the first winding, the first winding being arranged in series with the timer contacts, the second winding being arranged in series with the two normally open contacts of the switch means and with the timer contacts, d. relay contact means including, i. a contact arm, and ii. a normally closed contact, the contact arm and the normally closed contact being in series connection with the timer contacts, the upper arm of the switch means and the alarm means, wherein the first relay winding is dimensioned such as to produce an electro-magnetic force of attraction sufficient to hold the relay contact arm in an attracted position once the contact arm has been moved there by the combined electro-magnetic force of attraction of the two relay windings. 